I calculate the change of total homicides and average homicide rates for 5 year intervals, i.e. 1946-50 vs 1951-55 etc. Changes are always nominal, i.e. if there were 10 total homicides in 1946-50 and 15 total homicides in 1951-55, then the change is 5. If the average homicide rate was 0.2 in 1946-50 and 0.1 in 1951-55, then the change is -0.1.
I define a notable decline or a notable rise as the top 15% percent of rises and top 15% of declines in a given year for a given metrics.
I then interact these notable declines or rises with black residency according to 1950 maps and riots in the 40s and 50s.
## # A tibble: 13 × 2
## flag count
## <chr> <int>
## 1 Black Residency Likely Since 1939 & Black Migration 91
## 2 Black Residency Likely Since 1939 & No Black Migration 20
## 3 Likely No Black Residency in 1939 & Black Migration 27
## 4 No Black Residency in 1950 641
## 5 Notable Decline & Black Residency Likely Since 1939 & Black Migration 9
## 6 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 1
## 7 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 8 Notable Decline & No Black Residency in 1950 5
## 9 Notable Rise & Black Residency Likely Since 1939 & Black Migration 19
## 10 Notable Rise & Black Residency Likely Since 1939 & No Black Migration 2
## 11 Notable Rise & Likely No Black Residency in 1939 & Black Migration 1
## 12 Riot in This Half-Decade & Black Residency Likely Since 1939 & Black M… 3
## 13 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 13 × 2
## flag_sorted count
## <chr> <int>
## 1 No Black Residency in 1950 641
## 2 Black Residency Likely Since 1939 & Black Migration 91
## 3 Likely No Black Residency in 1939 & Black Migration 27
## 4 Black Residency Likely Since 1939 & No Black Migration 20
## 5 Notable Rise & Black Residency Likely Since 1939 & Black Migration 19
## 6 Notable Decline & Black Residency Likely Since 1939 & Black Migration 9
## 7 Notable Decline & No Black Residency in 1950 5
## 8 Riot in This Half-Decade & Black Residency Likely Since 1939 & Black M… 3
## 9 Notable Rise & Black Residency Likely Since 1939 & No Black Migration 2
## 10 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 1
## 11 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 12 Notable Rise & Likely No Black Residency in 1939 & Black Migration 1
## 13 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 13 × 2
## flag count
## <chr> <int>
## 1 Black Residency Likely Since 1939 & Black Migration 89
## 2 Black Residency Likely Since 1939 & No Black Migration 21
## 3 Likely No Black Residency in 1939 & Black Migration 25
## 4 No Black Residency in 1950 641
## 5 Notable Decline & Black Residency Likely Since 1939 & Black Migration 15
## 6 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 2
## 7 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 8 Notable Decline & No Black Residency in 1950 4
## 9 Notable Rise & Black Residency Likely Since 1939 & Black Migration 15
## 10 Notable Rise & Likely No Black Residency in 1939 & Black Migration 3
## 11 Riot in Previous Half-Decade & Black Residency Likely Since 1939 & Bla… 3
## 12 Riot in Previous Half-Decade & No Black Residency in 1950 1
## 13 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 13 × 2
## flag_sorted count
## <chr> <int>
## 1 No Black Residency in 1950 641
## 2 Black Residency Likely Since 1939 & Black Migration 89
## 3 Likely No Black Residency in 1939 & Black Migration 25
## 4 Black Residency Likely Since 1939 & No Black Migration 21
## 5 Notable Decline & Black Residency Likely Since 1939 & Black Migration 15
## 6 Notable Rise & Black Residency Likely Since 1939 & Black Migration 15
## 7 Notable Decline & No Black Residency in 1950 4
## 8 Notable Rise & Likely No Black Residency in 1939 & Black Migration 3
## 9 Riot in Previous Half-Decade & Black Residency Likely Since 1939 & Bla… 3
## 10 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 2
## 11 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 12 Riot in Previous Half-Decade & No Black Residency in 1950 1
## 13 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 14 × 2
## flag count
## <chr> <int>
## 1 Black Residency Likely Since 1939 & Black Migration 87
## 2 Black Residency Likely Since 1939 & No Black Migration 21
## 3 Likely No Black Residency in 1939 & Black Migration 25
## 4 No Black Residency in 1950 633
## 5 Notable Decline & Black Residency Likely Since 1939 & Black Migration 12
## 6 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 1
## 7 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 8 Notable Decline & No Black Residency in 1950 10
## 9 Notable Rise & Black Residency Likely Since 1939 & Black Migration 20
## 10 Notable Rise & Black Residency Likely Since 1939 & No Black Migration 1
## 11 Notable Rise & Likely No Black Residency in 1939 & Black Migration 3
## 12 Notable Rise & No Black Residency in 1950 3
## 13 Riot in This Half-Decade & Black Residency Likely Since 1939 & Black M… 3
## 14 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 14 × 2
## flag_sorted count
## <chr> <int>
## 1 No Black Residency in 1950 633
## 2 Black Residency Likely Since 1939 & Black Migration 87
## 3 Likely No Black Residency in 1939 & Black Migration 25
## 4 Black Residency Likely Since 1939 & No Black Migration 21
## 5 Notable Rise & Black Residency Likely Since 1939 & Black Migration 20
## 6 Notable Decline & Black Residency Likely Since 1939 & Black Migration 12
## 7 Notable Decline & No Black Residency in 1950 10
## 8 Notable Rise & Likely No Black Residency in 1939 & Black Migration 3
## 9 Notable Rise & No Black Residency in 1950 3
## 10 Riot in This Half-Decade & Black Residency Likely Since 1939 & Black M… 3
## 11 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 1
## 12 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 13 Notable Rise & Black Residency Likely Since 1939 & No Black Migration 1
## 14 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 14 × 2
## flag count
## <chr> <int>
## 1 Black Residency Likely Since 1939 & Black Migration 84
## 2 Black Residency Likely Since 1939 & No Black Migration 21
## 3 Likely No Black Residency in 1939 & Black Migration 26
## 4 No Black Residency in 1950 634
## 5 Notable Decline & Black Residency Likely Since 1939 & Black Migration 17
## 6 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 2
## 7 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 8 Notable Decline & No Black Residency in 1950 7
## 9 Notable Rise & Black Residency Likely Since 1939 & Black Migration 18
## 10 Notable Rise & Likely No Black Residency in 1939 & Black Migration 2
## 11 Notable Rise & No Black Residency in 1950 4
## 12 Riot in Previous Half-Decade & Black Residency Likely Since 1939 & Bla… 3
## 13 Riot in Previous Half-Decade & No Black Residency in 1950 1
## 14 Riot in This Half-Decade & No Black Residency in 1950 1
## # A tibble: 14 × 2
## flag_sorted count
## <chr> <int>
## 1 No Black Residency in 1950 634
## 2 Black Residency Likely Since 1939 & Black Migration 84
## 3 Likely No Black Residency in 1939 & Black Migration 26
## 4 Black Residency Likely Since 1939 & No Black Migration 21
## 5 Notable Rise & Black Residency Likely Since 1939 & Black Migration 18
## 6 Notable Decline & Black Residency Likely Since 1939 & Black Migration 17
## 7 Notable Decline & No Black Residency in 1950 7
## 8 Notable Rise & No Black Residency in 1950 4
## 9 Riot in Previous Half-Decade & Black Residency Likely Since 1939 & Bla… 3
## 10 Notable Decline & Black Residency Likely Since 1939 & No Black Migrati… 2
## 11 Notable Rise & Likely No Black Residency in 1939 & Black Migration 2
## 12 Notable Decline & Likely No Black Residency in 1939 & Black Migration 1
## 13 Riot in Previous Half-Decade & No Black Residency in 1950 1
## 14 Riot in This Half-Decade & No Black Residency in 1950 1
Notes on Highways: https://docs.google.com/document/d/1VVL-i87A_hBrtvJCNCINOAzE-xXXuCf4xSevoAj3nxA/
The tables below use preliminary data on highway construction dates. I combine these with a) changes in homicides and b) series of homicide snapshots over time.
Eisenhower Expressway
Edens Expressway
Bishop Ford Freeway / Calumet Expressway
Stevenson Expressway
Kennedy Expressway
Dan Ryan Expressway
Chicago Skyway
Intends to investigate homicide patterns around areas where riot takes place.
(Annoying color changes for a given riot are noted, I just haven’t spent the time to fix it.)
1947: Fernwood Park housing project, August 13th, 1947 to August 16th, 1947
1953: Trumbull Park, 1953-1954
## [1] "year_riot"
## [1] "in_check"
## [1] "still_desi"
## [1] "def_decl"
## [1] "hazardous"
## [1] "industrial"
## [1] "best"
## [1] "commercial"
## [1] "bk_res_1"
## [1] "bk_res_2"
## [1] "bk_res_3"
## [1] "bk_res_4_1"
## [1] "bk_res_4_2"
## [1] "bk_res_4_3"
## [1] "bk_res_5_1"
## [1] "bk_res_5_2"
## [1] "bk_res_5_3"
We see polygons where the percentage of 1% concentration is lower than 10% or 90%. There are very few instances where the difference is large (more than 10 percentage points difference in area mapped), and most occur in the south of Chicago where the maps were a) most distorted and b) the least amount of development matches the present state.
It may be best to use the 90% value rather than the 10% or 1% value in these instances. This is further corroborated by the original maps. The areas plotted below where the difference is highest appear to be of fairly equal size in all three maps.